Natural hydrocarbon production method



tates NATURAL HYDROCARBON PRODUCTION METHOD No Drawing. Application May18, 1953, Serial No. 355,856

Claims. (Cl. 252-855) This invention is concerned with an improvedmethod for the production of crude petroleum products. Moreparticularly, it relates to an improved process for the prevention ofcorrosion under anaerobic conditions such as occur in wells producinghydrocarbon gases or liquids in their natural state.

Hydrocarbon producing wells are roughly divided into two main classes,namely, those producing a preponderance of gas (referred to hereinafteras gas wells or gascondensate wells) and, secondly, those wellsproducing a preponderance of liquid products (hereinafter referred to asoil wells). In both instances a greater or less proportion of an aqueousphase is almost always present, usually in the form of a salty brine.Dissolved in this aqueous phase and forming a part of any gaseous orliquid phase are also acidic substances such as carbon dioxide, hydrogensulfide and organic aliphatic acids such as acetic and propionic acids.

Under the conditions of temperature and pressure existing within thewell, these systems, particularly in the presence of the acidicsubstances, cause a substantial amount of corrosion of corrodible metalparts, such as well casing, or tubing, sucker rods and the like. It hasbeen found that the type of corrosion which occurs is largely pittingcorrosion such as is encountered in metal failure generally referred toas corrosion fatigue, as well as severe localized attack whereby failureoccurs by penetration of the metal wall or by tensile failure due toweakening of the metal. This type of corrosion can and does occur Withinthe well in the absence of air or other oxygen-containing gas.Consequently, it will be evident that the corrosion occurring underthese anaerobic conditions does not result in the formation of variousoxides or rust but, on the contrary, consists in the formation ofrelatively insignificant amounts of solid corrosion products. Damage inthe form of pits in turn, under stress of the metal part, e. g., amoving sucker rod, creates cracks, leading to failure of the metal.

Many attempts have been made to correct this situation by the additionof a wide variety of materials to the oil or gas well, by coating themetallic parts with non-metallic films; by use of expensive alloysteels, such as stainless steel; or by the use of non-metallic wellparts, such as plastic piping and the like. In spite of the large amountof work performed in the past, the best that can be said is that acertain amount of reduction in the corrosion rate has been accomplishedwithout reaching a completely satisfactory solution to the problem.

In the course of this work, commercial substances known for theirinhibiting value in other systems have been investigated. It shortlybecame apparent, however, that the particular set of conditions existingin gas and oil wells caused most of these materials to be largelyineffective. This was particularly true of those agents formerlyutilized as rust inhibitors etfective for the prevention of corrosioncaused by the formation of iron oxides in substantially large amountsand in oxygen-containing atmospheres at ordinary temperatures. It wasfound that 2,753,612 Patented Sept. 18, 1956 most rust inhibitors wereeffective at or about atmospheric temperatures, but rapidly decreased incorrosion protective value with increase in temperatures, such asencountered in oil and gas wells.

It is an object of the present invention to provide an improved processfor the production of hydrocarbons from their natural reserves. It isanother object of the present invention to provide an improved processfor the reduction in corrosion occurring in the sweet and sour wellssuch as gas condensate wells. It is a further object of this inventionto substantially depress the corrosion fatigue ordinarily found inpumping oil wells. Other objects will become apparent from the followingdescription of the invention.

Now, in accordance with the present invention it has been found thatcorrosion occurring under anaerobic conditions in hydrocarbon producingwells is substantially repressed by the addition to said wells of apolymerized (especially dimerized) fatty or hydroxy fatty acid and/ orcertain derivatives thereof. Still in accordance with this invention,the useful life of metal well parts being subjected to mechanical stressis substantially prolonged by combination of said polymerized acids withan oleophilic organic phosphorus compound. Moreover, the phosphoruscompounds act as an aging stabilizer for the dimer acids, particularlyif stored in contact with air or under hot-or humid conditions. Again inaccordance with one phase of the present invention the introduction ofthese compositions into the hydrocarbon well is facilitated by combiningtherewith a water-dispersible detergent and washing the modifiedcomposition to the bottom of the well with water. One important aspectof the invention comprises the fact that the dimer acids and theirequivalents increase in the corrosion protection property at elevatedwell temperatures and under anaerobic conditions as compared to thedecreased effect with increasing temperature experienced when air ispresent, such as in a pipe line or storage tank.

In general, the dimeric acids have been produced by heat polymerizationof esters of the mono-carboxylic acids to esters of the dimeric acidsfollowed by hydrolysis. The glycerides have also been heat polymerizedand the product hydrolyzed to yield the free dimeric acids. Recently,Goebel in U. S. Patent No. 2,482,761 disclosed that the free fatty acidscan be polymerized. Briefly, Goebels process comprises preparingunsaturated fatty acids by hydrolyzing a fat or oil for example, soyabean fatty acids, adding a small portion of water, and heating in apressure vessel until substantially all of the diand tri-unsaturatedfatty acids present polymerize. The resultant product can then be heatedat reduced pressure, to distill off vaporizable constituents, whichinclude mainly saturated acids and mono-unsaturated acids. A temperature of at least 260 C. must be used and preferably from 330 C. to360 C. and a heating period of 3 to 8 hours to produce substantiallycomplete polymerization of diand tri-unsaturated material. Numerouscatalysts can be employed but are not necessary. Among the catalystswhich can be used are mercuric acetate, lead acetate, anthraquinone, andRancy nickel.

Thus, for example, as described in U. S. Patent No. 2,482,761, 300 partsby weight of sardine oil having an iodine value of 188 was pressuresplit with 600 parts of water at 260 C. Three treatments of 1 /2, /2 and/2 hour duration were used with parts of the water employed in eachtreatment. Water was withdrawn and the wet acids were heated to 350 C.at a pressure of 250 pounds per square inch for 4 /2 hours. The productwas then heated at reduced pressure to distill oif unpolymerizedmaterial yielding 44% by weight of a residue having an iodine value of86.3 and a neutralization equivalent of 386.

In a similar manner, as described in the aforesaid patent linseed fattyacids, soya bean fatty acids and the fatty acids of other drying orsemidrying oils can be polymerized to produce what the patentee namesdimeric acids. The patentee states that by his process larger yields ofdimeric acids are formed and less of the trimeric and higher polymericacids are formed.

Another source of dimeric acids is the still residue of the drydistillation of castor oil in the presence of sodium hydroxide. Ananalysis of the fatty acids from castor oil has been reported in Chem.Abs. 34, 3521 as follows:

Percent 87 7 Ricinoleic acid Oleic acid Linoleic acid Saturated acidsDistillation of the aforesaid still residue yields two approximatelyequal fractions, the distillate and a second still residue. Thedistillate is a mixture of undccylic, palmitic and stearic acidstogether with minor amounts of unsaturated monomeric fatty acids. Thesecond still residue is a mixture of which about 50% by weight ispolymerized fatty acids having a molecular Weight of 360 to about 600and the balance a still residue having a molecular weight in excess of600.

The material of the first still residue of the dry distillation ofcastor oil in the presence of sodium hydroxide has the followingproperties:

Lot 1 Lot 2 Neutralization N o 164 159. 9 Bromine No 26. 7 19. 4Kinematic Viscosity at 100 F. 3, 096 1, 373 Lovibond color 750 750 A. P.I. Gravity, degrc 14. 6 l5. 2 Specific Gravity 0. 9685 0. 9646 r H a:(CHz)sC=(Z-Ofi HG C a(CH2);CH H

FORMULA I This compound after hydrolysis yields the free acid saving thestructure shown in Formula II, or isomers hereof:

FORMULA II The octadecadienate esters dimerize by 1,4-diene addition toa compound having the structure shown in Formula III, or isomers of it.

FORMULA III This dimer upon hydrolysis yields the free acid having thestructure given in Formula IV, or isomers of it.

FORMULA IV When one of the free octadecadienoic or octadecatrienoicacids is polymerized as described in U. S. Patent No. 2,482,761, thepatentees dimeric acids have the structures shown in Formula II and IV,or isomers of them.

Castor oil contains ricinoleic acid in the form of a glyceride. The mostimportant pyrolytic reaction of ricinoleic acid and its esters is thatof dehydration to produce octadecadienoic acids. Therefore, in the drydistillation of castor oil in the presence of sodium hydroxide thehigher boiling portion, i. e., the still residue is a mixture ofpolymerized octadecadienoic acid derived from the ricinoleic acid andthe linoleic acid present in the castor oil.

From the foregoing a generic formula for the dimeric acids of thepresent invention can be written. Thus, as an example of anoctadecadienoic acid, the polymerization of linoleic acid isillustrative. Linoleic acid or A9,10,12, 13-octadecadienoic acid ispresent in peanut, palm, olive, teaseecl, kapok, etc., oils in amountsof less than 25%.

" Oils such as corn, germ, cottonseed, sunfiowerseed, poppyseed, sesame,etc., contain 40% to 60% linoleic acid. The linoleic acid obtained fromthe great majority of plant sources is A9,10,12,13-octadecadienoic acid.

When 139,10,12,13-octadecadienoic acid is dimerized in the absence ofother polyethenoid acids, either as an ester or as the free acid in themanner described in U. S. Patent No. 2,482,761, a reaction which takesplace can be illustrated by the following formula:

where R is CHa(CI-I2)4 and R is {CH2)7COOH. However, for the variousisomers of linoleic acid R will have a different value. Thus, artificiallinoleic or octadecadienoic acids have their origin in three naturalsources, (1) fatty acids more highly unsaturated than linoleic acid,which on partial hydrogenation form isomeric acids, (2) normal linoleicacid whose double bonds may be shifted by isomerization catalysts and(3) monoethenoid hydroxy acids, such as ricinoleic acid, which ondehydration form an additional double bond. For example, ricinoleic aciddehydrates to two isomeric linoleic acids, A9,l0,11,12-octadecadienoicacid and A9,10,12,13-octadecadienoic acid. WhenA9,10,11,12-octadecadienoic acid dimerizes in the absence of otherpolyethenoid acids, the resulting dimeric dicarboxylic acid has theformula:

where R is CH3(CH2)4- and R is (CH2)1COOH However, when themonocarboxylic acid is A8,9,12,13- isomer the dimeric dicarboxylic acidhas the structure:

carboxylic acid has the structure where R is CH3(CH2)3 and R is-(CH2)7COOH. It follows that when the A9,l0,l2,l3-isomer is dimerized isdimerized R is when the A8,9,12,13-isomer is dimerized R is CH3(CH2)5and R is --(CH2)6COOH; and when the A9,10,13,14-isomer is dimerized R isCH3 (CH2)4- and R is (CH2)1COOH. For these 4 isomeric linoleic acids thegeneric structure for the dimeric acid can be written where R isCH3(CH2) 4 for the A9,10,12,13-isomer and the A9,10,1l,12-isomer, andCHs(CH2)sfor the A8,9,- 12,13- and A9,10,l3,14-isorner, R is-(CHz)-zCOOH for the A9,10,11,12- and A9,10,13,14-isomers and (CH2)6COOHfor the A8,9,12,13-isomer, it becomes obvious that in the genericformula for the dimeric acids derived from the individual diethenoidmonocarboxylic acids R will have a significance of CH3(CH2)1L where n isone more than the number of CI-Izgroups between the terminal CH3 groupand the nearer carbon of the nearer double bond and R will have thesignificance (CH2)mCOOH in which m is the number of CH2- groups betweenthe carboxylic groups of the monocarboxylic acid and the nearer carbonof the nearer double bond. From this it follows that the generic formulafor dimeric acids derived from a single di-ethenoid monocarboxylicaliphatic acids is where R is CH3(CH2)1L and R' is (CH2)mCOOH and n andm have the values given hereinbefore.

When polyethenoid acids, i. e., triand greater ethenoid acids such asn-linolenic acids are dimerized, the dimeric acids obtained are bicyclicdicarboxylic acids having the formula with a shift of the double bondsat 15 and16 the formula of the dimeric acid becomes:

H (OHzhC O OH n-oioa go-(omnooon When A9,l0,l1,12,13,14-octadecatrienoicacid is the sole acid polymerized to form the dimeric dicarboxylic acidthe condensation can be pictured as occurring as follows:

which with the shift of the double bond at 11a and ll becomes H(CHQTCOOII CHaCHzCHzCHz-ll 120-11 The generic formula for the dimericdicarboxylic acids derived from the dimerization of individualtriethenoid octadecatrienoic acids is where R is CH3(CH2)3 and R is(CH2)'7COOH A well known source of these dimeric acids is the productsold by Emery Industries, Inc., and said to be dilinoleic acid. In theliterature published by the Emery Industries, Inc. the properties ofthis product are given as follows:

Neutral equivalent 290-310.

Iodine value 80-95.

Color Gardner 12 (max). Dimer content Approx. 85%. Trimer and higherApprox. 12%. Monomer Approx. 3%.

Tests of several batches of material supplied by this producer indicatethat the properties of this product are Within the limits set forthhereinafter:

Specific gravity, A. P. I l5--l5.l Specific gravity, D60/60 0.9665Dolor, Lovibond Kinematic viscosity at 100 F., centistokes 2462-2666 a.S. T. M. bromine No 2.. 39.3 leutrality No 186.8 l90.4 dine value 67-86It will be noted that the dimeric acids available from the EmeryIndustries, Inc., contain approximately 85% dimeric acids and about 12%trimeric and higher polymeric acids and the second still residue of thedry distillation of castor oil in the presence of sodium hydroxidecontains about -50% of the dimeric acids and about of the trimeric andhigher polymeric acids. Since neither of these industrially availableproducts is 100% dimeric acids it is manifest that materials containingmore highly polymerized acids than the dimeric acids can be used.However, it is to be noted that these ma terials contain only smallamounts, say less than 10% of the monocarboxylic or unpolymerized fattyacids and saturated acids.

Accordingly, preferred materials are those containing not more thanabout 15% of unpolymerized unsaturated fatty acids and saturated fattyacids. In general, the content of dimeric acids and trimeric and higheracids should be of the order of at least about 85% with the dimericacids representing at least about 50% of the dimeric and higherpolymeric acids. Thus, the Emery Industries dimeric acids contain about85% dimeric acids while the second still residue of the dry distillationof castor oil in the presence of sodium hydroxide contains about 46.8%dimeric acids. Those skilled in the art will recognize that the lowerthe concentration of dimeric and higher polymeric acids the greater theamount of the mixture required to provide the protection against theformation of corrosion.

While it is preferred to employ the dimerized acids described above, itis possible to utilize certain derivatives thereof, particularly theamine salts, amides or esters. 'Ihe amine salts are particularly usefulin oil or gas wells containing hydrogen sulfide, e. g., sour gas wells.It has been found that the amine salts are more satisfactory forcorrosion inhibition under such conditions than are the free acids.

Wells containing hydrogen sulfide (normally referred to as sour wells)are usually particularly dimcult to inhibit with respect to pittingcorrosion and metal fatigue. It has been found that the subject classesof dimerized acids, particularly when they are in the form of theiramine salts, substantially completely inhibit the corrosion which occursin such systems. The amines may be primary, secondary or tertiaryamines, preferably alkyl or hydroxy alkylamines. Suitable lowermolecular weight alkanolamines include monoethanolamine, diethanolamine,diaminoisopropanol, dipropanolaminc, triisopropanolamine, andbutanolamines. These may be added in the form of their salts with thedimerized acids or the amines and acids may be added separately, thesalt formation then taking place in situ. When more hydrophobic saltsare desired, the higher aliphatic amines having aliphatic radicals of12-24 carbon atoms each may be employed in the form of dimer acid salts,including such amines as dodecyl amine, tetradccyl amine and octadecylamine, as well as their mixtures with analogues such as derived fromnatural sources.

In utilizing the subject dimerized acids in gas condensate wells, it ispreferred that a sutlicient amount be employed, so that theconcentration is at least about 0.005% by weight based on thehydrocarbon phase. When utilized in oil wells, it is preferred than anamount effective to reduce corrosion fatigue, in the order of at leastabout 0.005% by weight, based on a hydrocarbon is present, although anamount of at least 0.01% is preferred. Amounts above about 0.10% fail toproduce any additional corrosion protection beyond that obtained withthe smaller amount noted above.

In accordance with a preferred variation of this invention, thedimerized fatty acids are combined with a phosphorus-containinghydrophobic organic wear reducing compound. This material is preferablypresent in an amount suflicient to provide between about 0.1% and about1% of phosphorus, based on the weight of the dimerized acids. Thephosphorus additives which have been found to be most effective compriseespecially the following classes:

(1) Reaction products of phosphorus sulfides with unsaturated organiccompounds, particularly with non-benzenoid unsaturated alicyclichydrocarbons such as terpenes. One suitable material satisfactory forthis purpose and belonging to the subject class bears the trade nameSantolene 394-C. This is a reaction product of a phosphorus sulfide witha terpene, apparently pinene. These reaction products may be obtained byreaction of a phosphorus sulfide at temperatures above about 100 C. witha bicyclic terpene. Phosphorus sulfides which may be utilized in thisand other reactions noted below are: P386, P486, P285, P487, P4510, etc.Suitable terpenes in addition to pinene include camphene and fenchene.Naturally occurring materials such as turpentine or pine oil may beemployed. It is preferred that a ratio of about 1 mole of a phosphorussulfide to between 3 and 5 moles of bicyclic terpene be employed,although the most suitable ratio is 1 mol of P285 to about 4 moles ofterpene.

A second preferred class of phosphorus anti-wear agents comprises thereaction products of phosphorus sulfide or phosphorus oxides and sulfurwith cylic ketones. These substances are described in U. S. Patents2,482,762 and U. S. 2,502,408. The cyclic ketones which may be employedmay be saturated or unsaturated and containing at least 12 andpreferably at least 18 carbon atoms per molecule. Typical cyclic ketonescomprise the isophorone bottoms obtained in the condensation of acetone.

A further class of phosphorus compounds comprises organicpolyphosphates, preferably the alkyl or aryl derivatives oftripolyphosphoric acid or the analogous tetraphosphoric acid. Thecations may be alkali metals, alkaline earth metals and amphotericmetals, such as sodium, calcium, barium, aluminum, or chromium. Suitablephosphates include potassium pentamethyl diphosphate, lithium pentaethyltriphosphate, calcium pentabutyl triphosphate, pentaisoamyl sodiumtriphosphate, sodium hexamethyl tetraphosphate and the like. Furtherspecies of substances useful for the process comprise the alkaline earthor amphoteric metal di-triphosphates such as described in U. S. Patent2,358,305: reaction products of phosphorus sulfides with mixtures ofnon-benzoid cyclic alcohols and fatty alcohols, as well as the reactionproducts of phosphorus sulfides with high molecular weight ester waxes.

In addition to the above-identified classes of phosphorus-containingcompounds, other materials may be employed such as the esters ofphosphorus acids including triaryl phosphates, such as tricresylphosphate, trialkyl phosphates, including trioctyl phosphate, andanalogous aralkyl and alkaryl phosphates, thiophosphates, phosphites andthiophosphites.

The subject protective agents have been found to be effective under awide variety of operating conditions. This is evident from the fact thatthey are highly efiective both in gas-condensate wells as well as inordinary oil wells. Moreover, they are effective not only for theprotection of stationary well parts from pitting and similar types ofanaerobic corrosion, but as stated hereinbefore, they are additionallyeffective for the prevention of wear in moving well parts such as suckerrods and the like.

The conditions which exist in gas-condensate wells will vary overwell-known broad areas. The liquefied hydrocarbon phase ingas-condensate wells normally comprises mixtures of methane, ethane,propane, butane, and higher hydrocarbon condensates up to and includinglight gasolines having up to about 8 carbon atoms. Normally gaseoushydrocarbons are partly liquefied in the well because of the pressuresordinarily existing therein. A

typical gas-condensate well produces between 20 and 30 barrels of aliquefied hydrocarbon phase per million cubic feet of gas (mmcf.), at atypical well head temperature and pressure. The temperatures at thebottom of the well usually range from about C. to about C., averagetemperatures at the well head being usually in the range of from about45 C. to about 80 C. Pressures in a condensate well usually range fromabout 1000 to about 7000 lbs. per sq. inch absolute. A typical well mayhave a bottom hole pressure of about 2700 p. s. i. a. and a flowingtubing pressure of about 2000 p. s. i. a. The pressure increases theratio of gaseous carbon dioxide (present in condensate wells) which willdissolve in the aqueous phase also present therein. At well headconditions there is usually a range of from about 7 to about 20 gallonsor higher of liquid water per million cubic feet of gas produced. Thisliquid phase contains carbon dioxide, thus providing the aqueouscarbonic acid phase. The latter usually has a pH value ranging fromabout 3.3 to a pH of 5.5. This aqueous phase may also contain sodiumchloride and other electrolytes, the usual amounts of which arewell-known to the art. Aqueous carbonic acid phase mixed with agitatedliquefied hydrocarbon phase and gases is usually distributed throughoutthe flowing system of the well.

The conditions present in oil wells are well-known in the art.Ordinarily, the temperatures will be between about 60 F. and about 250F. and pressures between atmospheric and about 5000 pounds per squareinch are encountered. They will vary according to the age of the well inaddition to the variations caused by the geologic formation from whichthe petroleum products are being obtained. The proportion of brine oraqueous phase will vary largely with the age of the well, but is alwayspresent to a greater or lesser degree, depending upon the particularwell. The requirement for pumping will depend upon the pressures presentin the well, which may be varied by water-flooding or gas repressuringtechniques as known in the art.

In injecting the inhibitors into gas or oil wells, they may be packagedin the form of a cartridge, the casing of which (e. g. gelatin) isselected to melt at temperatures existing in the well. Amounts ofdetergents up to about 2.5% based on the dimer acids may be added to thelatter when they are not packaged and if they are to be washed down thewell with water, since the unmodified acids are oleophilic and are noteasily moved in a water stream in the absence of the detergent. Thelatter may be a carboxylic acid soap, e. g. sodium stearate, or alkalimetal sulfate or sulfonate, or a nonionic detergent such as polyalkyleneoxide or glycol condensation products with polyhydroxy compounds such assorbitan. The preferred method of treating a well comprises a specialsoaking procedure, wherein production is halted for a period of /2-3days, during which the well is filled with oil containing Water (orbrine) and dimer acids For an obscure reason, the presence of 1%100%water, based on the oil, during this soaking treatment causes anincrease of 50100% in the effectiveness of the dimer acids.

In a laboratory test, similating conditions encountered in sweetgas-condensate wells, the following comparative data were obtained.These tests were carried out in fourounce oil sample bottles, containinga /8 x 5 inch sandblasted specimen of cold-rolled carbon steel. Thebottles contained 50 ml. kerosene, 10 ml. distilled water whichcontained 3% sodium chloride, 0.1% calcium chloride, 0.03% magnesiumchloride, and 0.1% acetic acid. The bottles were rotated end over end at60 R. P. M. for 24 hours at 180 F. The specimens were then cleaned byimmersing with gentle agitation for 1 minute in concentratedhydrochloric acid containing 5% SnClz and 2% SbzOa. The specimen wasthen neutralized immediately in sodium bicarbonate solution, rinsed withwater and dried. Controlled cleaning loss was 3 milligrams and thecorrosion rate was calculated from net weight loss. In the tabulationwhich follows the inhibitor concentration was based on the hydrocarbonphase. The inhibitor employed comprised a mixture of dimerized fattyacids ob- 1.1 tained by known dimerizing procedures with vegetable oilacids.

Corrosion Rate l\[l1s Percent by weight of Additive per Year When usingproportions of additives in the order of 0.001% the following substanceswere found to have substantially the same corrosion protection propertyas experienced with the above dimer acids: dimers of castor oil acids; amixture of amine salts and amides of dimerized linoleic acid anddialkanol amine; and dimerized soy bean oil.

The additives may be injected into the well either continuously orintermittently. In many cases it is advantageous to be able to make thisinjection at stated intervals. Consequently, the persistence ofcorrosion inhibition is an important factor when judging the efiicacy ofan inhibitor. It was found that the subject dimerized fatty acidseffectively inhibited corrosion over periods up to at least 2 days afterthey had been washed out of the system.

This was determined by subjecting specimens to the action of theinhibtors under the conditions described above, then draining thespecimens and replacing them in bottles containing uninhibited keroseneand brine. When the original concentration of dimerized acids wasbetween about 0.01% and about 0.05% the rate of corrosion did notincrease even after two days of treatment in the uninhibited keroseneand brine.

in determining the effect of the present additives upon the life ofmoving well parts, tests in the Krause constant deflection fatiguemachine were conducted. The machine was adapted for /s" by 4- /2 longspecimens of sucker rod alloy. The test section was encased in aneoprene cell through which the oil and brine mixture (800 ml. totalvolume) was circulated at 300 ml. per minute. The tests were conductedat 150 F., the specimens being stressed to a maximum of 50,000 p. s. i.outer fiber stress at 825 cycles per minute. Crude oil and brine wereused in 20/80 ratio quantities. Under these conditions the sucker rodfailed after one million one hundred thousand cycles. However, when theoil and brine were modified by the presence of 0.01% dimerized acidscontaining a phosphorus anti-wear agent, the sucker rod lasted for fivemillion three hundred fifty thousand cycles before failure. Thephosphorus additive employed in these tests was the reaction productobtained by treatment of pinene oil with P235 at about 100 C., known asSantolene 394C. It was present in an amount sufiicient to provide themodified dimerized acid with a phosphorus content of about 0.4% byweight. The combination of dimer acids and phosphorus compound was acommercial product bearing the trade-name Santolene C.

Analysis of the dimer acid product employed in these tests indicatedthat it was a mixture of dimers together with a small amount ofmonomeric acids and a substantial proportion of trimers and higherpolymers. The average molecular weight of the entire mixture was about600.

We claim as our invention:

1. The method of treating a liquid hydrocarbon-containing system in itsnatural state in a pumping well for the purpose of inhibiting corrosionand reducing wear of well parts under anaerobic condition, said systemcomprlsing a liquefied normally liquid hydrocarbon phase and a minoramount of an aqueous acid, said system in a state of mechanicallyactuated flow at a temperature between about 60 F. and about 250 F. andat pressures between about atmospheric pressure and about 5,000 poundsper square inch absolute, comes in contact with corrodible well parts,which method includes the step of mixing with said system from about0.005% to about 0.1% of dimerized higher fatty acids, said acids havingat least two olefinic linkages per molecule based on the hydrocarbonphase and an oleophilic organic phosphorus compound in an amountsufficient to provide between about 0.1% and about 1% phosphorus basedon the weight of the dimerized acids.

2. A process according to claim 1 wherein the dimerized fatty acids aremodified by the presence of an oleophilic organic heat reaction productof phosphorus pentasulfide and pine oil.

3. A process according to claim 1 wherein the dimer acids are modifiedby the presence of a reaction product obtained by heating a phosphorussulfide with a bicyclic terpene.

4. The method of treating a liquid hydrocarbon-containing system in itsnatural state in a pumping well for the purpose of inhibiting corrosionand reducing wear of well parts under anaerobic conditions, said systemcomprising liquefied normally gaseous hydrocarbon phase and a minoramount of an aqueous acid, said system in a state of mechanicallyactuated flow at a temperature between about 60 F. and about 250 F. andat pressures between about atmospheric pressure and about 5,000 poundsper square inch absolute, comes in contact with corrodible well parts,which method includes the step of mixing with said system from about0.005% to about 0.1% of dimerized fatty acids, said acids having atleast two olefinic linkages per molecule, based on the hydrocarbon phaseand an oleophilic organic phosphorus compound in an amount sufiicient toprovide between about 0.1% and about 1% phosphorus based on the weightof the dimerized acids.

5. The method of treating a liquid hydrocarbon-containing system in itsnatural state in a pumping well for the purpose of inhibiting corrosionand reducing wear of well parts under anaerobic conditions, said systemcomprising liquefied hydrocarhon phase and a minor amount of an aqueousacid, said system in a state of mechanically actuated fiow at atemperature between about 60 F. and about 250 F. and at pressuresbetween about atmospheric pressure and about 5,000 pounds per squareinch absolute, comes in contact with corrodible well parts, which methodincludes the step of mixing with said system from about 0.005% to about0.1% of dimerized fatty acids, said acids having at least two olefiniclinkages per molecule, based on the hydrocarbon phase and an olephilicorganic phosphorus compound in an amount sulficient to provide betweenabout 0.1% and about 1% phosphorus based on the weight of the dimerizedacids.

References Cited in the file of this patent UNITED STATES PATENTS2,324,577 Haffner July 20, 1943 2,614,983 Caldwell et a1 Oct. 21, 19522,632,695 Landis Mar. 24, 1953

1. THE METHOD OF TREATING A LIQUID HYDROCARBON-CONTAINING SYSTEM IN ITSNATURAL STATE IN A PUMPING WELL FOR THE PURPOSE OF INHIBITING CORROSIONAND REDUCING WEAR OF WELL PARTS UNDER ANAEROBIC CONDITION, SAID SYSTEMCOMPRISING A LIQUEFIED NORMALLY HYDROCARBON PHASE AND A MINOR AMOUNT OFAN AQUEOUS ACID, SAID SYSTEM IN A STATE OF MECHANICALLY ACTUATED FLOW ATA TEMPERATURE BETWEEN ABOUT 60* F. AND ABOUT 250* F. AND AT PRESSURESBETWEEN ABOUT ATMOSPHERIC PRESSURE AND ABOUT 5,000 POUNDS PER SQUAREINCH ABSOLUTE, COMES IN CONTACT WITH CORRODIBLE WELL PARTS, WHICH METHODINCLUDES TH E STEP OF MIXING WITH SAID SYSTEM FROM ABOUT 0.005% TO ABOUT0.1% OF DIMERIZED HIGHER FATTY ACIDS, SAID ACIDS HAVING AT LEAST TWOOLEFINIC LINKAGES PER MOLECULE BASED ON THE HYDROCARBON PHASE AND ANOLEOPHILIC ORGANIC PHOSPHORUS COMPOUND IN AN AMOUNT SUFFICIENT TOPROVIDE BETWEEN ABOUT 0.1% AND ABOUT 1% PHOSPHOROUS BASED ON THE WEIGHTOF THE DIMERIZED ACIDS.